1. Field of Invention
The present invention relates to an irradiation device to test material using gamma rays radiated from a spent nuclear fuel assembly. In particular, in order to research a hardening process of material weakening due to radiation in atomic power facilities from gamma rays radiated from a spent nuclear fuel assembly, the present invention provides an irradiation device to test material, the device being capable of moving upward, downward and horizontally, thereby controlling a position of a spent nuclear fuel and a test material for a radiation test on the test material using gamma rays radiated from the spent nuclear fuel for accomplishing an evaluation of radiation effects. The present invention further provides an irradiation device for a material test using gamma rays radiated from a spent nuclear fuel assembly in which a scale is placed to discern a distance between the spent nuclear fuel assembly and a test material.
2. Discussion of the Background
A spent nuclear fuel generally generated at a nuclear power or nuclear fuel laboratory generates various kinds of radiation such as a particles, β rays, γ rays, neutrons, etc. and the materials of facilities for handling and storing the spent nuclear fuel are to be irradiated by such radiation rays in a large amount.
Therefore, various kinds of parts and devices constructed in the facilities for handling and storing the spent nuclear fuel are degenerated by being exposed to the radiation circumstance, and this is regarded as a main cause of a malfunction of the parts and devices used for handling the spent nuclear fuel or a decrease in the longevity thereof.
Therefore, in order to operate the facilities for handling and storing the spent nuclear fuel safely, it is important to evaluate the effects caused by radiation of various kinds on nuclear power material.
In order to do so, the experiments to identify a degeneration phenomenon of the materials exposed to radiation circumstance, need to consider effects caused by neutral particles, alpha particles and beta rays among the radiation generated from the spent nuclear fuel, which except for effects caused by gamma rays are so scarce, since experiments for identifying the degeneration phenomenon of the materials exposed to the radiation circumstance are performed under the gamma ray irradiation until now.
To perform such experiments, the existing facilities for an irradiation test using gamma rays have mainly used 60Co sources and the gamma rays evaluation test of gamma rays on materials are partially performed using 137Cs sources.
In the existing gamma ray irradiation facility, using 60Co sources and 137CS sources, where the gamma rays energies are at 1.17 MeV, 1.332 MeV and at 0.662 MeV respectively, cannot describe a various energy spectrum of gamma rays generated from a spent nuclear fuel and the effects thereof on material.
Since such energy and flux-to-dose-rate of gamma rays generated from a spent nuclear fuel assembly have a various spectrum according to burn-up, cooling time, position and distance of nuclear fuel assembly, it is required to develop and make an irradiation device to describe the various circumstances of gamma ray irradiation radiated from a spent nuclear fuel.